Cooling furniture comprising at least two thermally separate compartments

ABSTRACT

An item of cooling furniture includes two thermally separate compartments which are associated with respective evaporators. An expansion valve and evaporators are connected in series in a refrigerant circuit. The adjustment valve permits adjustment between different discrete flow coefficients.

The invention relates to refrigeration equipment comprising at least two thermally separate compartments, the evaporators of which, together with a compressor and a condenser, are located in a refrigerant circuit and to which liquid refrigerant is applied by the compressor on receipt of a signal that refrigeration is required in the compartments, whereby the degree of refrigeration contributing to the generation of refrigeration is controllable. Furthermore, the invention relates to a method suitable for operating this refrigeration equipment.

A wide variety of embodiments of refrigeration equipment for regulating different compartments of an item of refrigeration equipment to different temperature levels are known.

For example, German printed specification DE 23 50 998 discloses refrigeration equipment comprising a single circuit, which is embodied at low cost with merely a single entry point for the refrigerant into the evaporators. Evaporators are here associated with a freezer compartment and a normal refrigeration compartment in each case and are arranged one after the other in series in the refrigerant circuit. However, this arrangement in series of the evaporators has the disadvantage that it is necessary to dimension the individual evaporators in accordance with the refrigeration requirement existing in the individual compartments, or the temperature requirements pertaining there. Consequently the design of the evaporators cannot be optimized in respect of a desired energy efficiency, since to this end the evaporators would have to be designed to have as large a surface as possible. It is also a particular disadvantage that the temperatures of the individual compartments cannot be set independently of one another, since if in the case of such refrigeration equipment refrigeration is required in a compartment situated downstream in the refrigerant flow, refrigeration also takes place simultaneously in the compartments upstream of this compartment.

In the case of refrigeration equipment with multiple refrigeration compartments it is proposed, in order to be able to refrigerate these as independently of one another as possible, to associate individually controllable refrigerant circuits with the individual refrigeration compartments. Such refrigeration equipment is for example described in unexamined German patent applications DE 35 08 805 A1 or DE 40 20 537 A1. In this case the evaporators associated with the individual refrigeration compartments are arranged in parallel with one another in a refrigerant circuit. The entry points for the refrigerant into these evaporators have closable throttle valves. These throttle valves are individually controlled by a temperature regulator and are then opened by this if a refrigeration requirement is established in the respective refrigeration compartment. In the case of the refrigeration equipment described in DE 35 08 805 A1, a reservoir for temporary storage of liquid refrigerant is provided in the refrigerant circuit upstream of a junction leading to the evaporators. Additional refrigerant can be selectively introduced into the refrigerant circuit herefrom by heating the reservoir when more refrigeration is required, in particular when both evaporators are operating simultaneously. In the case of the refrigeration equipment described in DE 40 20 537 A1 the refrigerant to be introduced into the evaporators is extracted from the condenser in accordance with this requirement at one extraction point or simultaneously at several extraction points. A disadvantage with this prior art is that energy-consuming storage media or else inefficiently used condensers are used in order to control the variable quantity of refrigerant resulting from switching the individual evaporators on and off The parallel arrangement of a plurality of evaporators also results in significant additional cost compared to single circuits because of the two-fold design of the injection system (valve, throttle capillaries, injection point).

A single circuit, which can be realized at low cost and energy-efficiently compared to the above systems and which nevertheless is designed such that the individual refrigeration compartments of the refrigeration equipment can be regulated largely independently of one another in terms of temperature is described in unexamined German patent application DE 44 33 712 A1. In this case a plurality of evaporators are arranged in series in the refrigeration circuit, which are associated with a freezing compartment, a cold storage compartment and a normal refrigeration compartment in the flow direction of the refrigerant. In order to refrigerate the individual compartments of the refrigeration equipment individually, the quantity of refrigeration introduced into the chain of evaporators is selectively controlled. Whenever only the evaporator of the freezing compartment lying first downstream of the condenser is to be refrigerated, refrigerant is extracted from the refrigerant circuit and is temporarily stored in a reservoir. This results in a depletion of refrigerant in the evaporator chain, so that no more refrigeration takes place in the downstream evaporator of the normal refrigeration compartment. However, if this normal refrigeration compartment is now to be refrigerated, the flow of refrigerant coming from the compressor is routed through the reservoir by diverting the refrigerant circuit, so that as a result an increased quantity of refrigerant flows into the evaporators therefrom. Thanks to this diversion mechanism in the refrigerant circuit controlled by means of a magnetic valve, the quantity of refrigerant available can be controlled using minimum energy and in the same pass of the evaporators generate and temporarily store refrigerant without impediment for storage in the reservoir even if the requirement for refrigerant is small. Here too the connected refrigerant supply line through the reservoir or past it results in increased additional costs when manufacturing the refrigeration equipment.

The object of the invention is to find low-cost refrigeration equipment having at least two compartments thermally separate from one another as well as a method suitable for operating this refrigeration equipment, in which there is compartment-specific temperature regulation using just a single shared refrigerant circuit and a uniform, modular manufacture of the evaporator components is enabled.

The object is achieved by an item of refrigeration equipment and a method suitable for operating this refrigeration equipment, having the features of claims 1 and 8. Advantageous embodiments and developments of the invention are described by the subclaims.

In the case of the refrigeration equipment having at least two compartments thermally separate from one another, an evaporator is associated with each of these compartments. An expansion valve and these evaporators are arranged in series one behind the other in a refrigerant circuit. In inventive fashion, at least two states having different nontransient flow coefficients can be set at the expansion valve.

The invention is thus based on a selective alteration of the flow coefficient of an expansion valve in the refrigerant circuit of an item of refrigeration equipment. The refrigerant flow through the evaporators of the refrigeration equipment can be selectively altered hereby. In refrigeration equipment having a single circuit, this brings about an alteration in the ratio of liquid to gaseous refrigerant in the individual evaporators and thus an alteration of the refrigeration capacity available in the evaporators.

The variability of the refrigeration capacity achieved in this way means that the dimensions of the individual evaporators are no longer determined, as was normal in the past with refrigeration equipment having evaporators connected in series, by the expected ratio between the refrigeration capacities required in the individual compartments. The evaporators can thus be dimensioned to be large in size in respect of optimum energy efficiency.

The advantages of the invention are particularly relevant in multi-zone refrigeration appliances in which individual compartments such as a freezer compartment, normal refrigeration compartment, basement compartment and 0° compartment are to be supplied individually and actively regulated.

Since the evaporators of the refrigeration equipment can be freely designed or dimensioned thanks to the invention independently of the refrigeration requirement in the individual compartments, the revenue-making potential arises of producing multi-zone refrigeration equipment, the components of which (in particular evaporators) can be used uniformly (modularly) in large quantities and hereby open up the advantages of the refrigeration equipment known from the prior art in respect of energy efficiency and controllability.

When manufacturing the evaporators it is not here necessary for the individual refrigeration compartments of the refrigeration equipment to be manufactured as separate, individual components and to be made available for assembly on the refrigeration equipment. Instead it is especially advantageous to design the individual evaporators on a common support and thus to create an evaporator module which can be installed quickly and at low cost.

To permit a selective control or regulation of the refrigerant flow through the evaporators it is firstly conceivable to design the expansion valve such that its flow coefficient can be adjusted steplessly. Secondly it is also easily possible to embody the expansion valve with switchable discrete flow coefficients. Such discrete switchability is provided in particular in the case of embodiments of refrigeration equipment which have few compartments thermally separate from one another.

To be able to regulate the temperature in the refrigeration equipment particularly advantageously, it is possible to associate temperature sensors with the thermally separate compartments of the refrigeration equipment. These temperature sensors are then connected to an evaluation circuit for signaling a refrigeration requirement in the individual compartments, this evaluation circuit forming a part of a temperature regulator. If one of the temperature sensors signals to this temperature regulator that there is a refrigeration requirement in at least one of the compartments of the refrigeration equipment, the temperature regulator sets the flow coefficient of the expansion valve so that the refrigerant flowing through preferably evaporates in the compartment in which the refrigeration requirement was detected.

Further features and advantages of the invention emerge from the following description of exemplary embodiments, with reference to the enclosed figures. The drawing shows:

FIG. 1 an item of refrigeration equipment with an expansion valve according to the present invention,

FIG. 2 possible embodiments of a three-step switchable expansion valve that can be used in the refrigeration equipment.

In the case of the embodiment shown by way of example in FIG. 1 an item of refrigeration equipment having just two compartments has been used in order to simplify the illustration. Obviously the invention is not restricted to such an embodiment, but it can be transferred from this, by the actions of a person skilled in the art, to refrigeration equipment having any number of compartments.

FIG. 1 shows an item of refrigeration equipment 20 which has two compartments 21, 21′ that can be regulated to different temperatures. Each of the compartments 21, 21′ is associated with an evaporator 2, 2′. These evaporators 2, 2′ are located in a refrigerant circuit 1, through which refrigerant flows, in series downstream of a compressor 3, a condenser 4 and an expansion valve 5.

Each of the compartments 21, 21′ is associated with a temperature sensor 12, 12′. These temperature sensors 12, 12′ are connected to an evaluation circuit 11 for signaling a refrigeration requirement, said circuit forming part of a temperature regulator 10. In a manner known per se, the temperature regulator 10 activates the compressor 3 via a control line 14 if a refrigeration requirement is detected in one of the compartments, and deactivates it if no further refrigeration requirement is detected. In addition the temperature regulator 10 activates the expansion valve 5 via a control line 13 when signaling a refrigeration requirement in at least one compartment 12, 12′, in order to adjust the flow coefficients of the latter as a function of the refrigeration requirement detected.

So long as none of the compartments 21, 21′ has a refrigeration requirement and consequently the compressor 3 is deactivated, the expansion valve 5 is held shut by the temperature regulator 10. Because this prevents an equalization of pressure between condenser 4 and evaporator 5 during the service life of the compressor 3 an energy saving of approximately 3%-10% can be achieved, depending on the design of the refrigerant circuit.

In order to be able to introduce a larger quantity of liquid refrigerant at short notice into the evaporators 2, 2′ when there is a large refrigeration requirement, it is advantageous to introduce a reservoir 6 into the refrigerant circuit 1 downstream of the condenser 4, which serves to accommodate liquid refrigerant. Additional refrigerant can be introduced at short notice from here into the refrigerant circuit as required, for example by heating the reservoir 6.

If a refrigeration requirement is detected in one of the compartments 21, 21′ the simple design means that the temperature regulator 10 sets one of two discrete nontransient values of the flow coefficient at the expansion valve 5, namely a low value if refrigeration is required in compartment 21′ and a high value if refrigeration is required in compartment 21.

If the flow coefficient of the expansion valve 5 is set as small by the temperature regulator 10, more refrigerant is drawn through the compressor 3 from the evaporators 2, 2′ than is introduced via the expansion valve 5 into the evaporators 2, 2′. The pressure in the evaporators is low, and the evaporator temperature correspondingly low. In this way the refrigerant evaporates only in the vicinity of its outlet point from the expansion valve 5, in the evaporator 2′, and in essence only compartment 21′ is refrigerated.

If the refrigeration requirement exists in the evaporator 2 further distant from the expansion valve 5 along the flow path of the refrigerant, the flow coefficient of the expansion valve 5 is selected as large by the temperature regulator 10. Since less refrigerant is drawn through the compressor 3 than is introduced via the expansion valve 5 into the evaporators 2, 2′ the pressure in the evaporators and correspondingly also the boiling point of the refrigerant rises. If it is higher than the temperature of compartment 21′, the refrigerant flows through the evaporator 2′, without evaporating, and does not evaporate until it is in the evaporator 2 of the warmer compartment 21. In this way in essence only compartment 21′ is refrigerated.

An average flow coefficient can be selected if there is a refrigeration requirement in both compartments 21, 21′ simultaneously. Then in each case some of the refrigerant evaporates in evaporator 21′ and the rest in evaporator 21.

The same average flow coefficient can be selected if compartment 21′ has an unusually high refrigeration requirement, for instance when fast-freezing newly stored refrigerated goods.

According to an embodiment not shown in the drawing, an item of refrigeration equipment has three or more compartments refrigerated by evaporators connected in series, and an expansion valve arranged upstream of the evaporators in a refrigerant circuit can be switched between at least as many values of the flow coefficient as there are compartments present. In each case the values are selected such that when setting one of these values the evaporation of the refrigerant takes place predominantly in an evaporator associated with this value. The value of the flow coefficient associated with an evaporator is higher the further downstream the associated evaporator is located in the refrigerant circuit.

In order to set the required different values of the flow coefficient, an expansion valve having a steplessly controllable flow coefficient can be used. Expansion valves for which only a small number of discrete values of the flow coefficient can be set are especially simple and are sufficient for most applications.

In the case of the refrigeration equipment 20 sketched in FIG. 1, which has only two compartments 21, 21′ to be refrigerated, it is sufficient if two different nontransient flow coefficients of the expansion valve 5 can be set. This enables a very low-cost temperature regulation to be achieved, thereby enhancing revenue.

FIG. 2 shows three possible embodiments of an expansion valve 5 suitable for this. Common to all embodiments is the fork (for example by means of a T-piece) in the main supply line 31 of the refrigerant circuit at the inlet to the expansion valve 5 into two parallel line paths. A blocking element 30 is added to these two line paths subsequent to this fork. This blocking element 30, e.g. a directional control valve, has a first switching stage, in which both line paths are blocked, a second switching stage, in which one of the two line paths is open and the other is blocked, and a third switching stage, in which the other line path is open, it being possible for one line path in this third switching stage to be open or blocked. At the outlet of the blocking element 30 is a capillary tube 34, which discharges directly into the evaporator 21′ in known manner.

In the case of the exemplary embodiment of the expansion valve 5 sketched in FIG. 2 a) the parallel routed line paths mentioned above comprise capillary tubes 32, 33 of different lengths and the same cross-section upstream of the inlets of the blocking element 30. Depending on the switching stage of the blocking element 30, the refrigerant flows through the capillary tube 32, the capillary tube 33 or through both in parallel, from which in each case different flow coefficients of the expansion valve 5 result.

The same effect is achieved in the case of the embodiment of the expansion valve 5 sketched in FIG. 2 b) by using capillary tubes 42, 43 having different cross-sections.

In the case of the expansion valve sketched in FIG. 2 c) a capillary tube 52 is provided on only one of the two line paths; the other line branch 53 has no significant flow resistance on account of small length or large cross-section. If the blocking element switches its opening to line branch 53, this corresponds to a direct connection of the main supply line 31 to the capillary tube 34 located at the outlet of the blocking element 30. The line branch 53 thus forms a bypass around the capillary tube 52.

The embodiment of a multistage controllable expansion valve is of course not restricted to the versions shown in FIG. 2. Instead of the capillary tubes, diaphragms can be used in an otherwise commodious refrigerant line. More than two nontransient values of the flow coefficient can be achieved, in that a directional control valve with four settings, corresponding to the four possible combinations of “Open” and “Blocked” of the two line branches, is provided, or in that the main supply line 31 in the expansion valve 5 is split into more than two parallel, individually switchable line branches. 

1-11. (canceled)
 12. An item of refrigeration equipment comprising: at least two evaporators; at least two compartments thermally separate from one another, each of the compartments being operatively associated with one of the evaporators; and an expansion valve, the expansion valve and the evaporators being arranged one after the other in series in a refrigerant circuit through which refrigerant flows and the expansion valve being operable to set at least two states having different nontransient flow coefficients.
 13. The item of refrigeration equipment as claimed in claim 12, wherein the flow coefficient of the expansion valve is adjustable steplessly.
 14. The item of refrigeration equipment as claimed in claim 12, wherein the expansion valve is switchable between discrete values of the flow coefficient.
 15. The item of refrigeration equipment as claimed in claim 14, wherein the expansion valve includes two parallel line sections and a blocking element for blocking one of the two line sections in one of the two states.
 16. The item of refrigeration equipment as claimed in claim 12, wherein the expansion valve is operable to set a third state, the third state being a state that is non-permeable for the refrigerant.
 17. The item of refrigeration equipment as claimed in claim 12, wherein the evaporators are configured on a common support.
 18. The item of refrigeration equipment as claimed in claim 12 and further comprising a reservoir in the refrigerant circuit located downstream of a condenser and operable to accommodate and/or temporarily store liquid refrigerant.
 19. The item of refrigeration equipment as claimed in claim 12, wherein each of the thermally separate compartments is associated with a temperature sensor, each temperature sensor being connected to an evaluation circuit for signaling a refrigeration requirement that forms part of a temperature regulator.
 20. A method for operating an item of refrigeration equipment, the method comprising: detecting a refrigeration requirement in the compartments of the item of refrigeration equipment; and controlling, as a function of the item of refrigeration requirement, the supply of liquid refrigerant to evaporators associated with the compartments for generation of refrigeration and connected in series, wherein the control of the supply of refrigerant is effected by setting at least two states with different nontransient flow coefficients in a controllable expansion valve, the status being selected as a function of which of the compartments of the item of refrigeration requirement is detected.
 21. The method as claimed in claim 20, wherein, when detecting a refrigeration requirement in a compartment whose evaporator is a relatively long distance from the expansion valve, a high flow coefficient of the expansion valve is set and, when detecting a refrigeration requirement in a compartment whose evaporator is close to the expansion valve, a low flow coefficient of the expansion valve is set.
 22. The method as claimed in claim 20, wherein, if a refrigeration requirement exists in none of the compartments of the item of refrigeration equipment, the expansion valve is held closed. 